Gram negative commas Flashcards
What are the three gram negative, oxidase + comma shaped bacteria?
Campylobacter jejuni
Vibrio cholerae
Helicobacter
What differentiates C. jejuni from the other commas?
Grows at 42 degrees.
What differentiates V. cholerae from the other commas?
Grows in alkaline environment
What differentiates H. pylori from the other commas?
Produces urease
Where is v. cholerae endemic to?
Developing countries
What is the clinical presentation of v. cholerae?
Cholera: severe diarrhea with rice water stools.
How does v. cholerae attach to intestinal epithelium?
- Mucinase digests mucus layer so v. chol can attach
- Fimbriae helps attach
- Motile - single flagellum (H antigen).
What is the structure of the enterotoxin of v. cholerae and how does it work?
- Five Bsubunits bind to intestinal cell membranes
- Two Asubunits carry about ADP-ribosylation of GTP-binding protein, Gs: permanently active.
- Activates adenylate cyclase, which converts ATP to cAMP. Incr cAMP.
- cAMP induces secretion of NaCl and inhibits resorption
What is the cause of death in cholera?
Dehydration. Prompt oral rehydration is necessary.
What is the clinical presentation of campylobacter?
Bloody diarrhea, esp in children.
What is the transmission of campylobacter?
- Fecal oral transmission through person to person contract, via ingestion of undercooked poultry/meat/unpasteurized milk.
- Contact with infected animals (dogs/cats/pigs) also a risk factor
What can follow campylobacter infection?
Guillain-Barre syndrome.
How does campylobacter cause infection?
Has a similar toxin to choleragen and the LT toxin of E.coli.
Has a cytotoxin that destroys mucosal cells (can be invasive –> bloody).
In addition to being oxidase + and urease+, what other enzyme does h. pylori have?
Catalase +.
What disease manifestation does H. pylori cause?
Gastritis, peptic ulcers, esp duodenal.
